This invention relates to an improved moisture detecting device.
A wide variety of moisture detecting devices have been known in the art for quite some time. For example, enuresis bedpads have been designed with thin, metal, current conducting, sensor strips bonded to one surface of a sheet-like, essentially non stretchable, relatively flexible and electrically insulative substrat. An example of such a bedpad is disclosed in Shuman U.S. Pat. No. 3,778,570 which is designed to be fabricated in large rolls and then cut into appropriate lengths. The metal sensor strips are electrically insulated from each other by the substrat itself. Sensor tapes are also known in the art as exemplified by Tom U.S. Pat. No. 4,297,686. The Tom patent discloses a water detection device comprised of a flexible plastic tape with an adhesive backing and having a surface which contains a pair of conductive metal strips. The usual design of moisture sensing devices is represented by a pair of metal screens with replaceable padding between them. Further, some designs involve dissimilar metal such as aluminum and copper used as a generator of feeble electric currents to be detected by associated detector circuits. Still other inventions relate to a pad with numerous parallel but separate wires intermeshed so that moisture will form a conductive path between two wire grids.
Each of these previous devices have common defects in that they are composed of fragile metal wires which break with extended use and which may cause injury to the user who comes in contact with a broken strand of wire, cleaning them is quite difficult, replacement of padding is inconvenient, and the sensing device itself is usually uncomfortable. In addition, there is a general deterioration of most systems due to chemical corrosion by the electrolyte which comes in contact with the metal wires in the grid. A further major defect in previous devices is that once the electrolyte comes in contact with the sensing wires, removing the electrolyte completely and restoring the system to its detecting state is extremely difficult. Even removing and completely drying previous devices leaves some amount of electrolytic residue on the sensing wires so that after repeated use, previous devices suffer a gradual yet continual deterioration of performance. Thus, there is a need in the art for providing a moisture sensing means which avoids the hazards associated with the rapid deterioration of wire systems, which is easily located in the normal bedding already in use and which is flexible and small enough so that it cannot be a source of discomfort, while at the same time being capable of complete and easy cleaning. It, therefore, is an object of this invention to provide an improved moisture sensing device which is thin and flexible enough so that it may be located in normal bedding already in use without becoming a source of discomfort.
It is another objective of this invention to provide a sealed plastic device that uses non-metallic conductors and that is easily cleaned and dried for immediate reuse.
Yet another object of this invention is to provide electrical conductivity between two parallel non-metallic conductors in the presence of an electrolyte and yet provide complete chemical isolation between the conductors and the external environment.
It is still another object of this invention to provide a simple, sure means of attaching the device to ordinary bedding so that proper control of the position of the device in the probable wet area is provided.
It is yet another object of this invention to provide a moisture sensing strip for sensing of liquid levels in storage tanks.
It is yet another object of this invention to provide a sensing strip for sensing the presence of water or other electrolyte that might be spilled on a floor.